• Korean Journal of Mathematics
• /
• v.13 no.2
• /
• pp.161-176
• /
• 2005

We consider a model of population dynamics whose mortality function is unbounded. We note that the regularity of the solution depends on the growth rate of the mortality near the maximum age. We propose Gauss-Legendre methods along the characteristics to approximate the solution when the solution is smooth enough. It is proven that the scheme is convergent at fourth-order rate in the maximum norm. We also propose discontinuous Galerkin finite element methods to approximate the solution which is not smooth enough. The stability of the method is discussed. Several numerical examples are presented.

• Korean System Dynamics Review
• /
• v.16 no.3
• /
• pp.31-48
• /
• 2015

The purpose of this paper is to simulate drinking population, an alcoholic abuser and an alcoholic through therapy programs and system dynamic model. Then we try to research relationship between an alcoholic crime and related therapy programs. The results of the model simulation were consistently increased drinking population and 3 types drinkers until 2020 years. Specially the growth rate of drinking abusers will be passing that of a drinking population. Second, It showed clearly the decreasing effects of drinking crime on therapy programs(clinical treatment, preventive displine and counseling treatment). Finally, it will be positvely necessary the long-term and various alcoholic therapy program for reducing the ratio of drinking abusers and an alcoholic. In the second place, government and medical centers must be established a concrete information systems for collecting alcoholic datum.

• Journal of the Korean Society for Industrial and Applied Mathematics
• /
• v.27 no.2
• /
• pp.123-134
• /
• 2023

Disordered eating behaviors, such as overeating, are known to be contagious in the general population. The objective of our research is to find an optimal control strategy to reduce the social burden of unhealthy overeating behavior by establishing and analyzing a mathematical model for the social transmission dynamics of unhealthy overeating. We consider four compartments in the population: normal weight with normal eating behavior, normal weight with overeating behavior, overweight with normal eating behavior, and overweight with overeating behavior. Simulation results under various control scenarios show that integrated control measures may be necessary to reduce the growth rate of the overeating population.

• Korean Journal of Ecology and Environment
• /
• v.39 no.2 s.116
• /
• pp.226-235
• /
• 2006

Populations of Zacco koreanus, distributed in four different tributaries of mid-upper reach Nakdong River were investigated to analyze a length-weight relation and von Bertalanffy's growth model. Fish sampling was conducted by common method (cast net and kick net) during March to October 2005. Fishes caught in the field were identified immediately, and then individuals of Zacco koreanus were preserved in 10% formalin to further measure their total length and weight in the laboratory. As the results of the equation based on length-weight relation, values of parameter b on the population of all tributaries were greater than 3.0 and the value on Bohyeon Stream was the maximum (3.26), indicating that the fish in the stream became more rotund as the length increases. In the mean time, we examined Brody growth constant (k) induced by the von Bertalanffy's growth model, and we found more steady state population in Wi (-0.18) and Byeongbo (-0.21) Streams than in fan (-0.38) and Bohyeon (-0.37) Streams. The findings would be used to assess local water environment on tributaries of the Nakdong River with understanding of ecological characteristics on the population of Zacco koreanus, as well as provide us fundamental information on domestic study of fish ecology.

• Korean Journal of Agricultural Science
• /
• v.48 no.4
• /
• pp.987-1001
• /
• 2021

One of the most critical issues in the dairy industry, alongside the low birth rate and the aging population, is the decrease in demand for milk. In this study, the consumption trends of 12 major dairy products distributed in Korea were predicted using a logistic model, the Gompertz model, and the Bass diffusion model, which are representative S-shaped growth models. The 12 dairy products are fermented milk (liquid type, cream type), butter, milk powder (modified, whole, skim), liquid milk (market, flavored), condensed milk, cheese (natural, processed), and cream. As a result of the analysis, the growth potential of butter, condensed milk, natural cheese, processed cheese, and cream consumption among the 12 dairy products is relatively high, whereas the growth of the remaining dairy product consumption is expected to stagnate or decrease. However, butter and cream are by-products of the skim milk powder manufacturing process. Therefore, even if the consumption of butter and cream grows, it is difficult to increase the demand of domestic milk unless the production of skim milk powder produced from domestic milk is also increased. Therefore, in order to support the domestic dairy industry, policy support should be focused on increasing domestic milk usage for the production of condensed milk, natural cheese, and processed cheese.

• KDI Journal of Economic Policy
• /
• v.34 no.4
• /
• pp.1-26
• /
• 2012

Greenhouse gas emission policy in Korea and elsewhere is based on emissions projections, a key element of which is the projected path of structural change from high productivity growth to low productivity growth economic sectors given sector specific labor productivity growth, emissions abatement across sectors and population growth. Thus, it is important to model the source of the structural change to forecast emissions correctly. Using data for the Korean economy, this study constructs and quantitatively evaluates a model of structural change and green growth to generate policy implications for Korea and the international greenhouse gas debate.

• Animal Bioscience
• /
• v.34 no.4
• /
• pp.471-481
• /
• 2021

Objective: A comprehensive study was conducted to study the effects of partition of variance on accuracy of genetic parameters and genetic trends of economic traits in Vanaraja male line/project directorate-1 (PD-1) chicken. Methods: Variance component analysis utilizing restricted maximum likelihood animal model was carried out with five generations data to delineate the population status, direct additive, maternal genetic, permanent environmental effects, besides genetic trends and performance of economic traits in PD-1 chickens. Genetic trend was estimated by regression of the estimated average breeding values (BV) on generations. Results: The body weight (BW) and shank length (SL) varied significantly (p≤0.01) among the generations, hatches and sexes. The least squares mean of SL at six weeks, the primary trait was 77.44±0.05 mm. All the production traits, viz., BWs, age at sexual maturity, egg production (EP) and egg weight were significantly influenced by generation. Model four with additive, maternal permanent environmental and residual effects was the best model for juvenile growth traits, except for zero-day BW. The heritability estimates for BW and SL at six weeks (SL6) were 0.20±0.03 and 0.17±0.03, respectively. The BV of SL6 in the population increased linearly from 0.03 to 3.62 mm due to selection. Genetic trend was significant (p≤0.05) for SL6, BW6, and production traits. The average genetic gain of EP40 for each generation was significant (p≤0.05) with an average increase of 0.38 eggs per generation. The average inbreeding coefficient was 0.02 in PD-1 line. Conclusion: The population was in ideal condition with negligible inbreeding and the selection was quite effective with significant genetic gains in each generation for primary trait of selection. The animal model minimized the over-estimation of genetic parameters and improved the accuracy of the BV, thus enabling the breeder to select the suitable breeding strategy for genetic improvement.

• Journal of the Economic Geographical Society of Korea
• /
• v.14 no.3
• /
• pp.325-341
• /
• 2011

The population and employment of Cheongju have increased rapidly since the 1970s. This study examines the industrial employment change of Cheongju City and performs a shift-share analysis for the employment growth. The data used in this study are mainly from the 1985, 2000 and 2005 Census of Population and Housing. This study first explained the population change and industrial structure of Cheongju, then reviewed the development of shift-share models. Location quotients and specialization coefficients resulted from this study revealed the diversifying tendency in the urban industrial structure. Shift-share analysis employing the modified Arcelus model elucidated the favorable industrial mix and the competitiveness of industrial sectors. As a whole, Cheongju has advantageous industrial structure in comparison with that of the nation. All sectors of Cheongju except several services sectors grew faster than those of the nation and showed positive competitive effects. It is suggested to utilize more disaggregated industrial data in more fractured subperiod in order to pinpoint the competitive industries.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.36 no.4
• /
• pp.409-416
• /
• 2003

Marine populations are maintained through the processes of spawning, growth, recruitment, natural death and fishing in a marine ecosystem. Based upon each of these processes, a quantitative population dynamic model was developed to estimate damages in fishery production due to accidents in a fishing ground. This model was applied for the abalone culture grounds in Korean waters. Three components of damages were identified in the ecosystem of the abalone culture grounds, namely, physical damages in the substratum of the fishing ground, biological damages in the structure and function of the ecosystem, and damages in fishery production. Considering these three components the processes and durations of damages in fishery production were determined. Because the abalone population is composed of multiple year classes, damages influence all the year classes in the population, when they occur The model developed in this study is: $$y=(n_{\lambda}+1){\times}Y_E\;-\;\sum\limits^{n_\lambda-n_c}_{l=0}\;y_{n_c/i}$$ where, y is the expected damages in fishery production during the period of restoration of the damaged abalony population, $Y_E$ is the annual equilibrium yield, $n_{\lambda}$ is the maximum age in the population, $t_s$ is the year of damage occurrence, $n_c$ is the age at recruitment, and $\sum\limits^{n_\lambda-n_c}_{l=0}\;y\;_{n_c/i}$ is total expected lifetime catch of year classes which were recruited during the restoration period.

• Korean Journal of Food Science and Technology
• /
• v.37 no.5
• /
• pp.850-855
• /
• 2005

Model was developed to predict the growth of Listeria monocytogenes in raw pork. Experiment condition for model development was full 5-by-7 factorial arrangements of temperature (0, 5, 10, 15, and $20^{\circ}C$) and time (0, 1, 2, 3, 18, 48, and 120 hr). Gompertz values A, C, B, and M, and growth kinetics, exponential growth rate (EGR), generation time (GT), lag phase duration (LPD), and maximum population density (MPD) were calculated based on growth increased data. GT and LPD values gradually decreased, whereas EGR value gradually increased with increasing temperature. Response surface analysis (RSA) was carried out using Gompertz B and M values, to formulate equation with temperature being main control factor. This equation was applied to Gompertz equation. Experimental and predictive values for GT, LPD, and EGR, compared using the model, showed no significant differences (p<0.01). Proposed model could be used to predict growth of microorganisms for exposure assessment of MRA, thereby allowing more informed decision-making on potential regulatory actions of microorganisms in raw pork.